Cardboard box construction



June 22, 1937. WOLF 2,084,965

CARDBOARD BOX CONSTRUCTION Filed July 27, 1935 INVENTOR.

10x I Elias Lfo lf,

Patented June 22, 1937 UNITED STATES PATENT OFFICE CARDBOARD BOX CONSTRUCTION Application July 27, 1935, Serial No. 33,512

1 Claim.

My invention relates to cardboard boxes and aims to provide an article having a relatively high resistance to pressure.

A box in accordance with my invention may have a body section and a cover section of substantially the same construction, the cover section preferably enclosing the body section except on the bottom of the latter. In use, it is customary to stack such boxes in piles and in such conditions, or during transportation, they are often subject to vertical or other crushing stresses, which are taken by the side walls of the box sections, it having been found that the bottom wall of the body section and the top wall of the cover section need not be as'strong as the side Walls. I,

accordingly, make the side walls of the two sections of my box of double thickness, preferably cutting the material for each section out of a single sheet to form a blank, somewhat in the form of a cross, and folding over the arm portions of such cruciform blank to provide the double thickness for the side walls. If desired, the arm portions of the blank can be out long enough so that reinforcing flanges are provided extending from the edges of the two sections along the bottom and top walls thereof. However, the side walls of the box section cannot develop the full strength of their material unless the joints at the corners of the box maintain their shape under pressure, and I have found that by providing the double layer side walls with joints which are impervious to the weather, the boxes can maintain their strength indefinitely, and are sufiiciently rigid to develop the full strength of the material in the side walls. In this connection, it will be understood that ordinary cardboard, as made on the paper making machine, is formed in three plies, two outer plies or liners and an inner or filler ply. The stronger and better material is used for the outer or liner plies. Consequently, a box wall having two layers or thicknesses of cardboard or paperboard folded together includes four liner plies, whereas a box wall of the same total thickness but of only one layer or sheet contains only two liner plies. This difference is of particular importance in the joint structure at the corners. The joint structure according to my invention comprises a sheet-metal strip embracing the joint at each corner and having two rows of metal prongs struck therefrom and extenting into the side walls of the box. Owing to practical conditions met in manufacture, the metal prongs of the corner strip are carefully limited as to length. However, if the prongs do not quite pierce the inner face of the box, then, in case of the side wall of single thickness, the prongs pass through and engage only one liner ply when, in my invention, the side walls being of double thickness, the metal prongs pass readily through at least three liner plies. The corner structures of my box, therefore, are relatively rigid and enable the side walls to develop the full strength of the material employed therein.

The characteristics and advantages of a box, in accordance with my invention, will be more fully understood from the following detailed description of a box exemplifying my invention taken in connection with the accompanying drawing in which:-

Figure l is a perspective view of a box, parts being broken away and parts being shown in section for purposes of illustration.

Figure 2 is a perspective view of the body section of the box shown in Figure 1, the top section having been removed.

Figure 3 is a plan of a blank for use in forming one of the sections of a box such as that shown in Figure l, the outer ends of the arms of the blank having adhesive applied thereto.

Figure 4 is a plan view of the blank shown in Figure 3 after the arms have been flolded and two layers stuck together.

Figure 5 is a section on the line 5-5 of Figure 2.

Figure 6 is a fragmentary perspective view on an enlarged scale of one of the corners of the box section shown in Figure 2.

Figure 7 is a sectional detail on the line 1-1 of Figure 6.

The box l0 illustrated in the drawing comprises a top section 10a having a top wall l2 of single thickness and four side walls of double thickness, two of which are indicated'by reference characters l4-l4. The bottom section lb of box I0 is shown separately in Figure 2 and comprises a bottom wall I8 of single thickness and four side walls 20-20 of double thickness. In forming a box section such as IUa or lob, I prefer to cut a blank Illa: from a single sheet in such manner that blank I01: has a somewhat cruciform shape, being provided with four flaps lily-I0 projecting from the central rectangular portion of the blank I013. The rectangular center portion of blank Illa: forms the bottom wall l8 of the section "lb or top wall l2 of section Illa, while each of the flaps I011 forms one of the side walls of one of said sections. Flaps I011 are of a length twice the height of one of the said side walls and the next step after cutting out the blank is to apply an adhesive 22 to a strip along the outer end of each of said flaps I01! and then to crease and fold each flap along its center line to halve the length of the flaps, producing the result illustrated in Figure 4. The doubled flaps are then creased along the lines at which they connect with the body of the blank I02: and bent up at right angles thereto into position to form the side walls of one of the box sections Illa or lllb. As illustrated in Figures 1, 5 and 7, the side walls l4 and are thereby formed of two layers, the side walls of section loa each having outer layer Ma and inner layer l4b integrally united along their free peripheral edges, and the side walls 20 of section lllb each having the outer layer 20a and inner layer 20b united along their free peripheral edges 2|. While I have indicated that flaps lily are folded in the middle, thereby bringing the edge of the layer 20b against the bottom wall I8 as clearly shown in Figure 5, I may make the flap lily long enough to provide a reinforcing flange extending along the bottom l8 adjacent the edges. Also, similar internal flanges may be provided in connection with the edges formed along the top wall l2.

While adhesive is sufliciently reliable to be utilized during the manufacture of boxes to hold the inner and outer layers of the side walls in proper position during the manufacture, if adhesive is utilized to assist in forming the joints at the corners, the box structure as a whole is obviously subject to atmospheric influences, which may loosen the adhesive so that the corners separate under crushing stresses. I, therefore,-form the joints between the side walls i4, i4 and 20, 20, respectively at the corners of my box sections solely by pressing into the side walls two rows of metal prongs 2424, one on each side of the seam 26 of a given joint, said rows of metal prongs being fixed to a right angled stay plate 30 embracing the corner. Ordinarily, the prongs 24 are struck out of the plate 30 leaving openings 2441 along the edges of such plate. Prongs 24 are ordinarily of a length approximately the total thickness .of the walls l4 and 20. However, the prongs are not always: exactly the same length and sometimes are not pressed in always exactly to the same degree so that they do not always just penetrate the inner liner ply forming the inner face of the wall. If theside walls were of only a single layer, the grip of the prongs 24 on the walls would be then greatly deficient because the prongs would only pass through one liner ply. In accordance with my invention, however, the prongs 24 may miss penetrating the inner liner ply and still may penetrate and have a firm engagement with three liner plies, one on the outer surface of the wall and two at the interior surfaces of the two layers of the wall. Furthermore, the prongs 24 when in position, ordinarily curve or flare away from each other at their free or inner ends, whereas they are substantially straight and at right angles to the surface of the wall adjacent the plate 30. It will be seen, therefore, that prongs 24 have only very little holding eflect so far as the outer liner ply of the wall structure is concerned but have a firm holding engagement with the two intermediate liner plies in the arrangement illustrated in Figure 7 and, therefore, form a strong joint irrespective of whether they fully penetrate the inner liner ply of the wall or not.

Having thus described my invention, what I hereby claim as new and desire to secure by Letters Patent, is:

A polygonal cardboard box section formed of a cardboard blank having a central rectangular panel and four generally rectangular side panels integral therewith and extending from the respective sides thereof and having a width more or less approximately twice the height of the side walls of the box section, each of said side panels being folded back upon itself along a line parallel with the corresponding side of said central panel and at a distance therefrom more or less approximately one-half the width of such side panel;said side panels being folded to a position at a right angle to the central panel, along the respective sides thereof, with the juxtaposed ends of adjacent two-ply side panels in generally abutting relation to each other; the inner longitudinal marginal zones only of said folded sidepanel portions being adhesively secured to the juxtaposed portions of said side-panels, and a sheet-metal strip overlapping the abutting end zones of adjacent side panels and having prongs thereon extending into both adjacent layers of cardboard of each of said adjacent side panels, thereby forming the sole fastening connection between said adjacent two-ply side panels and forming an interconnection between the two adjacent layers of cardboard of each of said two-ply side panels along the end marginal zones thereof.

ELIAS WOLF. 

